Abstract: A case with a shape of a thin rectangular parallelepiped which incorporates a radio signal processing circuit is provided with a data input/output section disposed on its surface and a microphone and a speaker disposed on either longitudinal end of the surface. Disposed inside of the case is a linear antenna, which longitudinally extends and goes out of the case from its side, and is placed adjacent to the surface of the case. Thus, the antenna characteristics are protected from deterioration even when the device is used on the desk. Further, the speaker is disposed in one of the sections divided by the longitudinal center line on the case surface and the linear antenna is disposed in the other section. Thus, the antenna gain fluctuation caused by the human body can be prevented so that the stable antenna characteristics can be maintained without being affected by the environment of utilization.

Abstract: A two-stage power amplifier device for use in a digital hand-held radiophone includes a first and a second amplifier circuit. The first amplifier is an exciter-stage amplifier for receiving a high-frequency input signal corresponding to a modulation signal to generate an amplified signal at its output. The second amplifier is a final-stage amplifier connected to either the input signal or the output of the exciter amplifier. A detector circuit is connected to the exciter amplifier, for monitoring variations in a bias current to be fed to the exciter amplifier, and for generating a detection signal indicative of the current variation thus detected. A linearizer circuit is connected to the detector and the final-stage amplifier.

Abstract: The present invention relates to an apparatus for measuring antenna radiation efficiency, wherein a random field measurement method can be adopted. In this apparatus, a to-be-measured antenna and a standard antenna are situated in a frame. In the frame, a plurality of rods, which are horizontally movable and extend vertically, are supported. A plurality of radio wave scatterers whose intervals and curvatures can be determined at random are held to the rods. In the frame, a random field is created by the radio wave scatterers.